VCONST02390 - Zero-rating the construction of buildings: is a building being constructed: prefabricated buildings and building kits
For a building to be 鈥榗onstructed鈥� it need not be built entirely 鈥榦n site鈥�. Large components may be made 鈥榦ff site鈥� for assembly 鈥榦n site鈥�. At the extreme, the relocation of a whole building can be the construction of a building on its new site.
VCONST02550 provides guidance on whether the supply is made 鈥榠n the course of the construction鈥� and therefore zero-rated.